We will approach study of mitotic mechanisms by attempts to isolate functional mitotic organelles, namely the mitotic apparatus (MA) and cleavage furrows which can be reactivated in vitro. It is only in this manner that we will be able to test various theories of mitotic function. We will continue to study MA tubulin and utilize this tubulin in MA reactivation solutions. We will analyze the MA ATP-ases, MA calcium sensitizing proteins and the remnant which remains after removal of microtubules. We will continue studies of isolated cortices from clam and sea urchin eggs with the ultimate aim of isolating functional furrows. This may require the separate isolation of myosin which we obtain in actomyosin gels extracted from eggs. We have been able to obtain these extracts so as to separate the conditions under which they gel and under which the gel can be caused to contract. We wish to separate the myosin from these gels and to use it in connection with cortices to see if it will help preserve furrows which now disappear during cortex isolation. In the long run, we hope that isolation of components from MAs and furrows will allow us to design experiments leading to understanding of how karyokinesis and cytokinesis are coordinated to result in mitosis.